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U.S. installed wind and solar power capacities and projections, 1990–2050


Windpower is one of the fastest growing electricity generation technologies in the U.S. In 2005--2010, U.S. installed wind capacity grew at an average rate of 39% per year, bringing the end-of-2010 capacity to 40,267 MW. In the Transform case, Rocky Mountain Institute projects wind capacity to continue its rapid climb, reaching 580,000 MW by 2050.

While there is currently nearly 100 times as much windpower as solar power capacity installed in the U.S., solar is now the world’s fastest growing source of electricity, and Rocky Mountain Institute projects this capacity to grow even faster over the next 40 years. In RMI’s Transform case, there will be more than 1,000 GW of U.S. solar power capacity in 2050. This sounds ambitious, but is consistent with the actual history and scaling behavior of related industries like semiconductors and cellphones.

Together, in this scenario wind and solar will account for 71% of total U.S. installed capacity in 2050, up from 4.4% in 2010. Along with hydro, geothermal, and biomass, renewables will generate more than 80% of 2050 U.S. electricity.

Background on wind:

At the end of 2010, U.S. wind capacity could meet 2.9% of annual U.S. electricity demand. While the grid integration of variable generators such as wind does pose challenges to system regulation and load-following, several markets have now successfully demonstrated much higher percentages of wind penetration. In Colorado, the system managed by Xcel Energy is averaging approximately 11% of annual electricity provided by wind. In some windy, low-demand hours of the year, wind generation is much higher, sometimes nearing 40% of the electricity received by customers. Internationally, the U.S. ranks 12th in wind generation; front-runner Denmark’s end-of-2010 capacity can meet 26% of annual electricity demand from wind in an average wind year. In 2010, four German states (two coastal, two inland) got 43–52% of their annual electricity from windpower. Some parts of Denmark, Germany, and Spain generate and export a surplus of wind electricity in windy low-load conditions. Most regional U.S. markets are successfully achieving high levels of wind penetration with largely unchanged grid technology and operations. Continuing innovations in wind turbine technology, energy storage resources, and grid management (such as the use of updated forecasts and shorter dispatch horizons) will enable even more wind capacity growth.

Background on solar:

Utility-scale photovoltaics currently dominate the U.S. installed solar capacity. But in the Transform case, RMI envisions a network of interconnected microgrids, each largely powered by distributed renewable resources. Rooftop photovoltaics are a huge piece of this future, and would total 727 GW in 2050 in this scenario. Concentrating solar power, which uses mirrors and lenses to concentrate the sun’s energy onto a collector to heat a working fluid and then drive a conventional steam turbine, will also grow to 35 GW of installed capacity by 2050.


Ackerman, Thomas, and Poul Erik Morthorst. 2005. “Economic Aspects of Wind Power in Power Systems.” In Wind Power in Power Systems, 384-410. England: John Wiley and Sons, Ltd.

Exeter Associates, K. 2007. Review of International Experience Integrating Variable Renewable Energy Generation. California Energy Commission.

GE Energy. 2010. Western Wind and Solar Integration Study. Prepared for National Renewable Energy Laboratory.

Terra Magnetica. 2010. “Siemens Launches Permanent Magnet-Based Gearless Wind Turbine”. April 25. link

U.S. Energy Information Administration. 2010. "Electric Power Annual 2009". Washington, D.C.: U.S. Department of Energy, November 23. link

Wiser, Ryan, and Mark Bolinger. 2011. 2010 Wind Technologies Market Report. Lawrence Berkeley National Laboratory, June. link

Xcel Energy. 2010. “Xcel Energy’s Wind Energy Program.” Presented to Wind Energy Prediction - Research and Development Workshop, May 11. link

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